latte_web
Version:
289 lines (265 loc) • 7.76 kB
JavaScript
/**
* @class utf8
* @namespace latte_lib
* @module coding
*
*/
(function() {
/**
* @property version
* @type String
*/
this.version = "0.0.1"
var stringFromCharCode = String.fromCharCode;
/**
* @method ucs2encode
* @param {int[]} array 8byte int[]
* @return {string} output utf8String
* @since 0.0.1
* @sync
* @static
* @demo utf8.html {utf测试}
* @example
var Utf8 = require("latte_lib").utf8;
console.log(Utf8.ucs2encode([108,97,116,116,101,30340,19990,30028])) ;//"latte的世界"
*/
var ucs2encode = this.ucs2encode = function(array) {
var length = array.length;
var index = -1;
var value;
var output = '';
while (++index < length) {
value = array[index];
if (value > 0xFFFF) {
value -= 0x10000;
output += stringFromCharCode(value >>> 10 & 0x3FF | 0xD800);
value = 0xDC00 | value & 0x3FF;
}
output += stringFromCharCode(value);
}
return output;
}
/**
* @method ucs2decode
* @param {string} str utf8String
* @return {int[]} output 8byte int[]
* @since 0.0.1
* @sync
* @static
* @example
var Utf8 = require("latte_lib").utf8;
console.log(Utf8.ucs2decode("latte的世界")) ;//[108,97,116,116,101,30340,19990,30028]
*/
var ucs2decode = this.ucs2decode = function (string) {
var output = [];
var counter = 0;
var length = string.length;
var value;
var extra;
while (counter < length) {
value = string.charCodeAt(counter++);
if (value >= 0xD800 && value <= 0xDBFF && counter < length) {
// high surrogate, and there is a next character
extra = string.charCodeAt(counter++);
if ((extra & 0xFC00) == 0xDC00) { // low surrogate
output.push(((value & 0x3FF) << 10) + (extra & 0x3FF) + 0x10000);
} else {
// unmatched surrogate; only append this code unit, in case the next
// code unit is the high surrogate of a surrogate pair
output.push(value);
counter--;
}
} else {
output.push(value);
}
}
return output;
}
function createByte(codePoint, shift) {
return stringFromCharCode(((codePoint >> shift) & 0x3F) | 0x80);
}
function encodeCodePoint(codePoint) {
if ((codePoint & 0xFFFFFF80) == 0) { // 1-byte sequence
return stringFromCharCode(codePoint);
}
var symbol = '';
if ((codePoint & 0xFFFFF800) == 0) { // 2-byte sequence
symbol = stringFromCharCode(((codePoint >> 6) & 0x1F) | 0xC0);
}
else if ((codePoint & 0xFFFF0000) == 0) { // 3-byte sequence
symbol = stringFromCharCode(((codePoint >> 12) & 0x0F) | 0xE0);
symbol += createByte(codePoint, 6);
}
else if ((codePoint & 0xFFE00000) == 0) { // 4-byte sequence
symbol = stringFromCharCode(((codePoint >> 18) & 0x07) | 0xF0);
symbol += createByte(codePoint, 12);
symbol += createByte(codePoint, 6);
}
symbol += stringFromCharCode((codePoint & 0x3F) | 0x80);
return symbol;
}
/**
*
* @method encode
* @param {string} str utf8string
* @return {string} byteString
* @since 0.0.1
* @static
* @sync
* @example
var Utf8 = require("latte_lib").utf8;
log(Utf8.encode("latte的世界")) ;//latteçä¸ç
*
*/
var utf8encode = this.encode = function(str) {
var codePoints = ucs2decode(str);
// console.log(JSON.stringify(codePoints.map(function(x) {
// return 'U+' + x.toString(16).toUpperCase();
// })));
var length = codePoints.length;
var index = -1;
var codePoint;
var byteString = '';
while (++index < length) {
codePoint = codePoints[index];
byteString += encodeCodePoint(codePoint);
}
return byteString;
}
function readContinuationByte() {
if (byteIndex >= byteCount) {
throw Error('Invalid byte index');
}
var continuationByte = byteArray[byteIndex] & 0xFF;
byteIndex++;
if ((continuationByte & 0xC0) == 0x80) {
return continuationByte & 0x3F;
}
// If we end up here, it’s not a continuation byte
throw Error('Invalid continuation byte');
}
function decodeSymbol() {
var byte1;
var byte2;
var byte3;
var byte4;
var codePoint;
if (byteIndex > byteCount) {
throw Error('Invalid byte index');
}
if (byteIndex == byteCount) {
return false;
}
// Read first byte
byte1 = byteArray[byteIndex] & 0xFF;
byteIndex++;
// 1-byte sequence (no continuation bytes)
if ((byte1 & 0x80) == 0) {
return byte1;
}
// 2-byte sequence
if ((byte1 & 0xE0) == 0xC0) {
var byte2 = readContinuationByte();
codePoint = ((byte1 & 0x1F) << 6) | byte2;
if (codePoint >= 0x80) {
return codePoint;
} else {
throw Error('Invalid continuation byte');
}
}
// 3-byte sequence (may include unpaired surrogates)
if ((byte1 & 0xF0) == 0xE0) {
byte2 = readContinuationByte();
byte3 = readContinuationByte();
codePoint = ((byte1 & 0x0F) << 12) | (byte2 << 6) | byte3;
if (codePoint >= 0x0800) {
return codePoint;
} else {
throw Error('Invalid continuation byte');
}
}
// 4-byte sequence
if ((byte1 & 0xF8) == 0xF0) {
byte2 = readContinuationByte();
byte3 = readContinuationByte();
byte4 = readContinuationByte();
codePoint = ((byte1 & 0x0F) << 0x12) | (byte2 << 0x0C) |
(byte3 << 0x06) | byte4;
if (codePoint >= 0x010000 && codePoint <= 0x10FFFF) {
return codePoint;
}
}
throw Error('Invalid UTF-8 detected');
}
var byteArray;
var byteCount;
var byteIndex;
/**
* @method decode
* @sync
* @static
* @param {string} byteString bytes
* @return {string}
* @since 0.0.1
* @example
* var Utf8;
*
* var Utf8 = require("latte_lib").utf8;
*
*
* console.log(Utf8.decode("latteçä¸ç")) ; //latte的世界
*/
var utf8decode = this.decode = function(byteString) {
byteArray = ucs2decode(byteString);
byteCount = byteArray.length;
byteIndex = 0;
var codePoints = [];
var tmp;
while ((tmp = decodeSymbol()) !== false) {
codePoints.push(tmp);
}
return ucs2encode(codePoints);
}
// private method for UTF-8 encoding
var _utf8_encode = function (string) {
string = string.replace(/\r\n/g,"\n");
var utftext = "";
for (var n = 0; n < string.length; n++) {
var c = string.charCodeAt(n);
if (c < 128) {
utftext += String.fromCharCode(c);
} else if((c > 127) && (c < 2048)) {
utftext += String.fromCharCode((c >> 6) | 192);
utftext += String.fromCharCode((c & 63) | 128);
} else {
utftext += String.fromCharCode((c >> 12) | 224);
utftext += String.fromCharCode(((c >> 6) & 63) | 128);
utftext += String.fromCharCode((c & 63) | 128);
}
}
return utftext;
}
// private method for UTF-8 decoding
var _utf8_decode = function (utftext) {
var string = "";
var i = 0;
var c = c1 = c2 = 0;
while ( i < utftext.length ) {
c = utftext.charCodeAt(i);
if (c < 128) {
string += String.fromCharCode(c);
i++;
} else if((c > 191) && (c < 224)) {
c2 = utftext.charCodeAt(i+1);
string += String.fromCharCode(((c & 31) << 6) | (c2 & 63));
i += 2;
} else {
c2 = utftext.charCodeAt(i+1);
c3 = utftext.charCodeAt(i+2);
string += String.fromCharCode(((c & 15) << 12) | ((c2 & 63) << 6) | (c3 & 63));
i += 3;
}
}
return string;
}
}).call(module.exports);